A reinforced greenhouse might stand nearby, sheltering strawberries, lettuce and spinach, things nutritious as well as psychologically important to people on the surface of an inhospitable planet about 50 million miles from Earth.

This is the vision of eight students in the University of Colorado's aerospace engineering department, who are designing a Martian greenhouse that could produce food and oxygen for 20 years.

The team's initial work last semester won it a finalist position in NASA's second annual MarsPort, a contest designed to challenge upper-level engineering students and help space agency engineers refine their ideas about how to sustain astronauts on Mars.

The paper designs may be the closest the cash-strapped agency comes to putting people on Mars this decade. The National Aeronautics and Space Administration has neither the money nor the political support to plan a human mission, said Burke Fort of the Texas Space Grant Consortium, co-sponsor of MarsPort.

"But there is funding for some of the mission design work," he said. The idea of MarsPort, he said, is to inject innovation into the research, to provoke NASA engineers with novel ideas.

The suggestion that NASA engineers might incorporate some small piece of the students' work in a final design is powerful motivation.

Shawn Bockstahler said his friends' mouths hang open when he tells them what he's doing for his senior design project.

"They don't believe me," he said. "Technically, it's possible to get to Mars. It's just money and politics prevent it."

His team will nail down design details this semester and make a final presentation to engineers at NASA's Kennedy Space Center in May. NASA and the Texas and Florida Space Grant Consortia are co-sponsors of the contest.

The CU group is competing against teams from Cornell University, Olin College of Engineering, St. Louis University, the Universities of Florida, and the University of Central Florida.

Any entry deemed "exemplary" will win its designers $500, but the more important prizes are recognition, Fort said.

The students' plans have evolved in a ramshackle office. A box of donuts emits a stale perfume, books are stacked in precarious piles on shelves, desks and the floor.

"It's all design work, it's all on paper, sketches," said Jim Clawson, the only doctoral student on the team, which includes seven senior undergraduates.

For his Ph.D., Clawson is studying designs and materials that could be used for an inflatable Martian greenhouse, and his technical assistance has been invaluable to the group.

"I try to not make it my personal design competition," Clawson said. "I gave them the part that I work on a lot, and beyond that I am just a team member."

The greenhouse designs are a combination of ideas from team members and NASA. The main greenhouse shell is layered and reinforced to protect against radiation and stray meteorites. The pods are thinner and more translucent, and surrounded by light-collecting panels that double as thermal protection during Mars' cold nights.

Students must design water, heat and air pressure systems for both.

The greenhouse does not need to grow all of the astronauts' food; some would be carried from Earth with the crew, said Aaron Frey, a senior and the official public-relations manager of the team.

NASA requires student teams to explain their work to the community, so Frey and his colleagues have invited elementary and middle school students to visit next month.

"We'll set up little demos to show why greenhouses are warmer on the inside," Frey said. "Stuff to get them excited about space."